Question

As the title asks, are they any g++ builtin function (or any method) to know the class name from a class object pointer?
For instance,

class Base {
};
class A : public Base {
};
class B : public Base {
};

void some_func(Base *p) {
    printf("the name of class: %s", __some_g++_builtin_get_class_name(p) );
}

Similar to __PRETTY_FUNCTION__ in gcc builtin, I hope there would be a builtin function for g++ that help us analyze source code 🙂

Answer 1

You may be able to use typeid for this.

#include <cstdio>
#include <typeinfo>

class Base {
    virtual int foo() { return 0; }
};
class A : public Base {
};
class B : public Base {
};

void some_func(Base *p) {
    printf("the name of class: %s\n", typeid(*p).name() );
}

int main() {
    some_func(new A);
}

Unfortunately it will probably not do what you want unless your base class has at least one virtual function (otherwise the type information may not be available).

Unlike __PRETTY_FUNCTION__, the value you are looking for cannot be computed at compile time.